Electronic devices such as smartphones and tablet PCs may include antennas for performing wireless communication and data communication. The electronic devices may perform a set of communication functions by providing radiation power to antennas. The performance of an antenna such as a data transmission/reception speed may depend on the intensity of radiation power. The radiation power of an antenna may be determined within a specified range in consideration of specific absorption rate (SAR) (such as an amount of electromagnetic waves absorbed into the body) generated from the antenna. The electronic device may reduce the amount of electromagnetic waves absorbed into a user by lowering radiation power. Additionally, the electronic device may detect whether a user around approaches. Therefore the electronic device may reduce the generation of electromagnetic waves by lowering radiation power if the user is detected within a specified range.
The conventional techniques adjust radiation power on the basis of one threshold value applied to both the case that a user approaches an electronic device and the case that a user leaves an electronic device. For example, when a distance to a user is detected based on a change in a capacitance of a capacitor included in an electronic device, the conventional techniques reduce radiation power to a specified value when the capacitance is equal to or greater than a specified threshold value and raises the radiation power to a default setting value again when the capacitance is less than the specified threshold value.
However, in a proximity sensor system in which a change of capacitance is not constant when a user approaches and leaves to/from an electronic device, the conventional techniques may provide a low radiation power value that is not enough to efficiently perform transmissions and receptions even when a user is sufficiently away from the electronic device.